Don't half-ass two things. Whole-ass one thing.<p>When your attention is split on two different and identical campaigns, both of them will fail. Choose one and make it count.
My colleagues and I are building our own crowdfunding platform serving the humanitarian community and we've given your subject some thought. If you're not asking for the same thing, I think it doesn't hurt to spread auxiliary funding aspects, stretch goals and so forth for example across onto another platform. It might very well cut some of your fundraising momentum but it will get you some face-time in return in front of another audience which might help in the long term.
At first glance I'm not convinced to the idea, I'd assume that it's better to keep the community in one place. Reaching critical mass sounds easier with just one URL to share too.<p>I might like it if the fundraisers were complementary and addressed to the same target groups, but actually different.
The page you use for crowdfunding is just a front page. It doesn't make sense to have two front pages - it's confusing to the user.<p>Also Kickstarter requires you meet your goal in order to get any money. It would be a shame if you got half the money on IndieGoGo and your Kickstarter failed because of it.